Thing is, in CC, weren't the supposed best-of-the-best in the Acacia Dragoons (also a mixed male/female goup, btw) called the Four Devas?
It'd probably be better to stick with Guru on this as, first off, this became a hereditary position and her father had no male heirs, if I remember our backstory correct, and second, so as to not confuse the two groups.
True, but CC messed up a few things in that regard, that being one of them. The other is that 'dragoon' has never implied a warrior that uses swords or any sort of weapon other than a gun. A dragoon is a mounted musketeer, and is so named for the breath of fire - like a dragon's - that flames from the barrel of his musket. That aside, however, it might be seen that the warrior's connection to the ancient dragons, and their bearing of dragon-symbols, could give strength to the name being used for them, perhaps.
However, I think my strongest point in arguing this is that there was an allusion behind the existance of three, and only three, Guru's. To change that number, and add a fourth to their order, would disrupt this deft allusion. Moreover, 'deva' is not as major a term in CC, and I would not worry overmuch about confusion between the two or, at least, less so than the difficulty in inherent in the issue which I have just stated. The confusion of the groups is, to my mind, far preferrable than the disruption of the order of the Three.
Now, I have yet to read the plot as outlined (I would wish to do so on paper, but have yet to print it off)... I am not sure if it is apparent in this writing or not, but I am extremely muddle-headed, and have difficulty understanding and reading things to some extent. As such, I should not wish to read it until such a time as I am feeling more apt to it. But sufficed to say, from what you have said, I would recommend not making the Guru's a hereditary position. They seem nearly like the counsellors and chief advisors to the Zeal (I think this is even alluded to, in what one of Zeal says in Chrono Trigger, regarding the 'three Guru's who led Zeal', or something to that effect.) That said, I doubt that the position of counsellor would be hereditary, and would likely be rather drawn from the old and experienced of the lords and wise men - those who through years have proven themselves. Rather like the position of Poet Lauriate or something to that effect. Belthesar distinguished himself as a scientist, so was appointed such a post in the royal court. Judging by their high status, they may even have been lords prior to that time, as well.
But regardless, to have such a position as hereditary would pose a grave problem: one man may be wise and learned in a field, but it does not mean his scion is. My father is well-versed in matters of theology and the like, and I share something of his love of those things, but my younger brother is not quite so keen to them. In the same way, what should happen if, then, the postion of Guru of Reason were filled by a man that cannot think in such a way, and passes on this inability to his children as well? Wise men would need be drawn from the ranks of wise men, not inhereted. After all, it would not be wisdom to do otherwise.
And as a second point, I simply do not think the idea of a woman Guru works, and to my mind reflects strangely on the position of Guru. Firstly, at least to me, Guru always implies a man, never a woman. To make one a woman seems to me simply an attempt to equalize things across the sexes, but is not how things would work in real. Or, to put it more correctly, Zeal is an ancient culture. There were, mostly, strict lines in culture, about what people could hold what position. That of Guru seems to me one of those that would have been forbidden to women, at least in what I know of the form of ancient culture (some, it is true, freely allowed female rulers and the like - the Egyptians for example - but there they followed the practices of the male rulers, in Egypt even wearing the kingly beard.) The best solution I could think of to such a dilemma - and it is a dilemma of style and form, and to my eyes makes Zeal seem less as an ancient culture and more as a modern one - is to make a parallel order that is purely of women, the priestesses to the priests, so to speak. The female equivalent then could easily be Deva. This re-use would hardly be grievous - Black Wind is reused, after all. Then we could have three positions here as well, say the Deva of Ceremonies, or things to that effect. It would not be hard to have them intruduce themselves as the Deva of the Ceremonies, second of the womanly three, the ladies who sat across from the three lords.
In the end, I must say that it seems that a female fourth Guru seems more as what would happen in a fanfiction than in Crimson Echoes (which I hold to be far above fanfiction from what I have seen so far), and am merely attempting to keep it away from such ground.
Oh, sorry, didn't see your post, Hadriel. Well, to my mind, Deva worked because it is the real-life opposite to Guru. Personally, I never liked the sound of 'Guru' (if you've ever seen my story, I always name them 'Master'), so naturally prefer Oracle over Deva. I'll check the meaning of oracle, though. Hmmm... I thought it was Greek, I should have known better. It's Latin, oh well. I suppose thinking of the Oracle at Delphi deceived me. Hmmm... Oracle of the Ceremonies? Does that work? (that 'of the Ceremonies' I thought of today I thought worked interestingly.)